What can noncommutative probability tell about representation theory?
Claus Koestler (University College Cork)
Tuesday 29th October, 2013 16:00-17:00 Maths 416
Among the principal motivations of von Neummann to introduce rings of operators, nowadays called von Neumann algebras, was the investigation
of unitary representations of large groups. A prototype of such a large group is the group of all finite permutations. Its extreme characters had
been characterized by Thoma in the 1960s, and alternative proofs have been given by Vershik & Kerov in the 1980s, as well as by Okounkov
around 1995. But none of these proofs uses really an operator algebraic toolkit. Recently we have found a new purely operator algebraic proof
of Thoma's theorem which shows that Thoma's theorem is actually a noncommutative de Finetti theorem.
My talk will introduce into related new developments and is based in parts on joint work with Rolf Gohm.